ZIOSTAT(1m)ZIOSTAT(1m)NAMEziostat-- Report ZFS read I/O activity
SYNOPSISziostat [-hIMrzZ] [interval [count]]
DESCRIPTION
The ziostat utility reports a summary of ZFS read I/O operations. It
first prints all activity since boot, then reports activity over a
specified interval.
When run from a non-global zone (NGZ), only activity from that NGZ can
be observed. When run from a the global zone (GZ), activity from the
GZ and all other NGZs can be observed.
This tool is useful for determining if disk I/O is a source of applica‐
tion latency. Combined with vfsstat(1M), ziostat(1M) shows the rela‐
tive contribution of disk I/O latency to overall I/O (and therefore
application) latency.
OUTPUT
The ziostat utility reports the following information:
r/s reads per second
kr/s kilobytes read per second
actv average number of ZFS read I/O operations being
handled by the disk
wsvc_t average wait time per I/O, in milliseconds
asvc_t average disk service time per I/O, in milliseconds
%b percent of time there is an I/O operation pending
OPTIONS
The following options are supported:
-h Show help message and exit
-I Print results per interval, rather than per second (where
applicable)
-M Print results in MB/s instead of KB/s
-r Show results in a comma-separated format
-z Hide zones with no read I/O activity
-Z Print results for all zones, not just the current zone
OPERANDS
interval
Specifies the length in seconds to pause between each interval report.
If not specified, ziostat will print a summary since boot and exit.
count
Specifies the number of intervals to report. Defaults to unlimited if
not specified.
SEE ALSOiostat(1m), vfsstat(1m), mpstat(1m)NOTES
This utility does not show any ZFS write I/O activity. Most write
operations are asynchronous, so the latency of those operations commit‐
ting to disk is much less important that read latency.
The output format from ziostat may change over time; use the comma-sep‐
arated output for a stable output format.
May 2014 ZIOSTAT(1m)
